06/12/2026
“Rollin coal” isn’t as cool as it once “was”! 💨
Customer complaint was it blows more black smoke than it used to and feels sluggish.
We hooked up our boost leak tester, and had an immediate red flag… not building any pressure in the intake system. Searched around for a major leak and found nothing.
Hooked up the smoke machine to see if we could find the leak in a more hidden area… still nothing.
Questioning the EGR system at this point…
Sure enough when we hooked the boost leak tester up it pushed all the smoke out the exhaust and confirmed the EGR valve was stuck open, allowing flow from the intake system direct out to the exhaust on this LMM Duramax.